The present invention relates to a disk holding device for holding a disk in an optical disk drive or the like.
In recent years, a compact, lightweight, and slim optical disk drive has been increasingly developed so that the optical disk drive can be contained in a notebook type personal computer. With the development of such optical disk drive, a disk holding device, which is slimed down by self-locking a disk on a turntable, has also been developed.
Japanese Published Patent Application No. Hei.10-188418 discloses a conventional disk holding device in which a disk holding mechanism and a disk centering mechanism are integrated into a turntable unit so that a single spindle motor unit can hold every optical disk as well as simultaneously adjust the center position of the optical disk (hereinafter, referred to as centering). FIGS. 5 through 7 illustrate a disk holding device for holding a bonded disk (a DVD disk) which has been recently developed. FIG. 5 is a cross-sectional view of the disk holding device in the state where the disk is not loaded. FIG. 6 is a cross-sectional view of the disk holding device in the state where the disk is loaded. FIG. 7 is a top view of the disk holding device.
Hereinafter, the conventional disk holding device will be described with reference to the drawings.
A spindle motor 32 is mainly divided into a turntable unit 33 which holds a disk 23 and a driving unit 37 which rotates the disk 23. First of all, claw-shaped members 26 which interfere with an edge of an internal diameter portion of the disk 23 are provided in at least three positions on the turn table 21 to hold the disk 23. Each claw-shaped member 26 is pressed by an elastic member 27, and ribs 26a on both sides of each claw-shaped member 26 are supported by a straight guide (not shown) of a center hub 25. The driving unit 37 is a component which mainly makes up a magnetic circuit, and it comprises a rotor yoke 34, a magnet 35, a coil 36, a base plate 39, a metal bearing unit 38 which supports a spindle shaft 24 forcibly inserted into the turntable 21, and the like. The spindle shaft 24 slides on a thrust bearing 40. Further, a Hall element 41 is disposed on a flexible printed circuit, FPC 42.
Next, holding of the conventional disk and the operation of a centering ring will be described.
When the disk 23 is loaded, the disk 23 is put on the turntable 21 while slope portions 26b of the claw-shaped members 26 arranged in at least three positions are being pressed down from above. At this time, each claw-shaped member 26 slides along a guide (not shown) in the center hub 25 while giving a repulsive force to the elastic member 27, and hides in the center hub 25. Further, an under-internal-diameter edge portion 23a, which is a lower edge portion of the internal diameter portion of the disk 23, is engaged with an inclined portion 28a of the centering ring 28 just before the disk 23 adheres to a slip sheet 22 bonded on the turntable 21, and the disk 23 is held by the claw-shaped members 26 arranged in at least three positions while being pressed by the elastic members 27 again. At this time, since a force always acts in the direction in which the disk 23 is pushed up by three elastic members 29, the centering ring 28 can center the disk 23.
However, since, in this conventional structure, the centering ring 28 is arranged under the center hub 25, the timing at which the disk 23 is engaged with the inclined portion 28a of the centering ring 28 and the timing at which the disk 23 adheres to the slip sheet 22 bonded on the turntable 21 to be held by the claw-shaped members 26 are almost simultaneous. Therefore, if the disk 23 is obliquely inserted, the edge portion 23a under the internal diameter of the disk 23 is not correctly engaged with the inclined portion 28a of the centering ring 28, resulting in deterioration of centering accuracy.
Further, in order to slim down the products, the elastic members 29 for pushing up the centering ring 28 must be arranged at every 120xc2x0, i.e., in three positions, on the turntable 21, whereby the number of parts and the amount of assembly work are increased, resulting in increased costs of the products.
The present invention is made to solve the above-described problems and has for its object to provide a disk holding device which can slim down the products, can perform holding and centering of a disk with reliability, and further can reduce the number of parts and the amount of assembly work.
A disk holding device according to one embodiment of the present invention comprises a turntable which is provided rotatably by a driving mechanism; a center hub which generally engages with the internal diameter of a disk provided on the turntable; plural claw-shaped members which are contained in the center hub; elastic members which energize the plural claw-shaped members in the direction of the radius of the disk; a centering ring for adjusting the center position of the disk, which centering ring is positioned beneath the center hub and is movable in the direction vertical to the disk surface; an elastic member which energizes the centering ring in the direction along which the disk is pushed up; and an inclined portion which is provided in the centering ring and engages with the internal diameter of the disk; wherein the inclined portion is positioned on the periphery of the center hub, and engages with the internal diameter of the disk before a cylindrical portion of the internal diameter of the disk gets over the claw-shaped members.
According to the disk holding device constructed as described above, centering of the disk is performed before the disk is held on the turntable by the claw-shaped members, and thereafter the disk is held, whereby more accurate holding and centering of the disk can be realized.
According to the present invention, in the disk holding device as discussed above, the centering ring and the elastic member which energizes the centering ring in the direction along which the disk is pushed up are arranged in a space between a coil of the driving mechanism which rotates the turntable, and a bearing metal unit which supports a spindle shaft forcibly inserted into the turntable.
According to the disk holding device constructed as described above, vertical strokes of the centering ring can be increased without increasing the thickness of the products, and the inclined portion of the centering ring which centers the disk can be arranged on the peripheral side surface of the center hub, and further, the number of parts can be reduced, thereby realizing cost reduction.